feature(oss-697): remove stack

[fireridlle]

OSS-767 remove stack

When users execute sls remove the plugin has to remove fauna resources too. (note: user can execute sls fauna remove to run only the plugin logic without needs to remove cloud stack)

Requirements:

• Remove only those resources that created by pluginserverless.yml config has collections A and B. user manually created collections C .when users execute serverless remove the plugin must remove only what specified at the config (A and B ) and keep C

• Add top-level deleting policy. In that case, resource level deleting_policy has higher priority and as an outcome, only orders collection would be deleted

fauna:
  data:
    deletion_policy: retain
  collection:
    orders:
      name: orders
    customers:
      name: customers
      data:
        deletion_policy: destroy